1. Field of the Invention
The present invention relates to a display in which small diffraction gratings are arranged in units of dots on a surface of a flat substrate and, more particularly, to an inexpensive display having diffraction grating patterns which can be easily manufactured and can express a stereoscopic (three-dimensional) image having no image omissions.
2. Description of the Related Art
A display having a diffraction grating pattern by arranging a plurality of small dots each consisting of a diffraction grating on a surface of a flat substrate has been frequently used. A method disclosed in, e.g., Published Unexamined Japanese Patent Application No. 60-156004 is used as a method of manufacturing a display having a diffraction grating pattern of this type. According to this method, small interference fringes (to be referred to as diffraction gratings hereinafter) obtained by two-beam interference are changed in pitch, direction, and light intensity, and the resultant images are sequentially exposed on a photosensitive film.
In recent years, the present inventor has proposed a method of manufacturing a display having a diffraction grating pattern of a given graphic image in such a manner that an X-Y stage on which a flat substrate is placed is moved under the control of a computer using, e.g., an electron beam exposure apparatus, and a plurality of small dots consisting of diffraction gratings are arranged on the surface of the flat substrate. This method is disclosed in U.S. Pat. No. 5,058,992.
In a display manufactured by this method, however, an image input from an image scanner or the like or a two-dimensional image formed by computer graphics is used as an image for the display having the diffraction grating patterns. For this reason, a graphic image expressed by the diffraction grating pattern are located on the surface of the flat substrate on which the diffraction gratings are arranged, so that only a flat (two-dimensional) graphic image can be expressed. As a result, a stereoscopic (three-dimensional) image cannot be expressed, resulting in inconvenience.